Advanced integrated circuits typically contain a great number of semiconductor devices, such as transistors, capacitors, resistors and the like, which are formed on an appropriate substrate including a crystalline semiconductor layer. The integrated circuits further include contact structures that are used to electrically interconnect the semiconductor devices and overlying metallization layers.
Due to the continuous reduction of the feature sizes of semiconductor devices in modern integrated circuits, the number of contact structures for a given chip area, that is, the contact structure packing density, is increasing. This increase in contact structure packing density requires reduced feature sizes for contact structures. Reduced feature size for contact structures results in an increase in contact resistance. Therefore, increased contact resistance is an ongoing issue for the further reduced feature size of contact structures.
Conventional integrated circuit fabrication processes typically utilize a tungsten plug or fill metal that is encapsulated by a dual liner and cap. Typically the dual liner is formed from a titanium layer and a titanium nitride layer. The titanium layer is provided to reduce contact resistance between the contact structure and the underlying device or device contact. The titanium nitride layer is provided to block migration of any fluorine ions out of the fill metal, particularly a tungsten fill metal, and to provide a wetting layer for the deposition of the fill metal. As feature size is reduced, the dual liner consumes an increasing amount of chip area relative to the fill metal portion of the contact structure.
Accordingly, it is desirable to provide integrated circuits having improved contact structures and methods for fabricating such integrated circuits. In addition, it is desirable to provide integrated circuits having contact structures with reduced thickness barriers. Also, it is desirable to provide integrated circuits having contact structures with silicate barriers. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.